The disclosure relates to a method for starting up a vehicle having a hydrostatic additional drive and a corresponding vehicle having a hydrostatic additional drive.
In vehicles which are used on a substrate with low traction and/or with significant inclinations, for example lorries on building sites, it is known from the prior art to engage a hydrostatically driven front axle with a conventionally mechanically driven rear axle of the vehicle.
The publication DE 42 12 983 C1 and the publication DE 10 161 C2 each set out such a drive concept, in which an internal combustion engine mechanically drives, on the one hand, a rear axle and in addition a variable displacement pump. Hydraulic motors of the respective front wheels can be driven by the variable displacement pump.
The publication DE 41 10 161 C2 further discloses that the pressure control of the hydrostatic additional drive and consequently the torque control of the front wheels, together with the torque control of the rear wheels, is carried out by means of an accelerator pedal of the vehicle. This control is carried out at the same time for the rear wheels by means of the internal combustion engine and for the front wheels by means of a pressure control valve of the hydrostatic additional drive. In this instance, pressure medium can be conveyed to the hydraulic motors only when a gear output shaft is rotated. Consequently, when starting up, “fast running” of the rear axle is possible, which may lead to a loss of the lateral guiding and to an unstable travel state. It is further possible, when the rear wheels are already slipping, for it no longer to be possible to start up the vehicle in spite of the additionally produced drive torque of the front wheels.
In this regard, an object of the disclosure is to provide a method for starting up a vehicle having a hydrostatic additional drive and a corresponding vehicle having a hydrostatic additional drive, whose start-up behavior is stabilized.